[FIX] event: notify to attendee information because its partner by default
[FIX] event: notify to attendee information because its partner by default

Indeed when buying tickets for an event several registrations could be
linked to the same partner while having different information for email
and name on registrations themselves.

Let us therefore format the automated emails first to registration info
if present and fallback on partner.

closes odoo/odoo#37790

Signed-off-by: Thibault Delavallee (tde) <2d325771bb6e8870d87f0f3f7b45589a8338e550@openerp.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo